This invention relates to contact cleaner rolls for cleaning webs employed in paper making, printing apparatus, and the like. More particularly, this invention relates to an improved two cleaner roll turret for web cleaning apparatus which allows the web to be nipped between a cleaner or cleaning roller and an idler roller thereby eliminating any undesirable boundary layer of air which interferes with the attraction of the web to the cleaning roll.
Disclosed in U.S. Pat. No. 5,251,348 is a contact cleaner roll mechanism employing three, spaced, parallel cleaner rolls rotatably mounted on a rotatable turret which, periodically positions the surface of one of the contact rollers into registry with a contact roll cleaner, while maintaining the other two cleaner rolls in engagement with the web that is to be cleaned. Each cleaner roll comprises a steel roll coated with a tacky polymer surface, so that the two engage with the web transfer particles from the web to their tacky surfaces, while the third, inactive roller is cleaned by having such particles removed from its surface by the roll cleaner.
One of the problems encountered with this prior art device is the fact that each of the cleaner rollers is rotatably mounted on the associated turret, while the web, which passes over the two, operative cleaning rollers, is positively driven by web drive motors, so that rotation is imparted to the two active rollers by virtue of their tacky surfaces being engaged with the traveling web. The amount of tension between the cleaning roller surfaces and the web, therefore, is determined by the web speed, and the machine web tension set by operation of the web drive motors. Consequently as the machine speed increases the boundary layer of air between the web and the surfaces of the two cleaning rollers also increases, thereby decreasing the attraction of the web to the respective cleaning rollers. Consequently, with low web tensions, or low wrap angles over the respective cleaning rollers, the cleaning effectiveness of the two operative rollers is reduced.
It is an object of this invention, therefore, to provide for web cleaner apparatus an improved two roll cleaner turret which allows very rapid change of the two cleaner rollers, placing the surface of a new, clean cleaner roller into nipping engagement with the web, and at the same time placing the now-dirty cleaning roller surface into registry with the roller cleaner mechanism.
A further object of this invention is to provide a two cleaner roll turret which is readily adjustable to change the nip pressure between the web and the cleaner roll then in engagement with the web.
Still a further object of this invention is to provide a two cleaner roll turret in which the nip pressure adjustment device functions also as a shock absorber enabling the operative cleaner roll to be moved away from the associated customer roller if a web splice or other thickness anomaly occurs in the customer web during a cleaning operation.
Still other objects of this invention will be apparent hereinafter from the specification and from the recital of the appended claims, particular when read in conjunction with the accompanying drawings.
A web roll is rotatably mounted on a frame for rotation by a web that travels thereover during a web cleaning operation; and a roll cleaner is mounted on the frame to reciprocate in a path spaced from and parallel to the web roll. A rotatable turret shaft which is mounted on the frame between and in spaced, parallel relation to the web roll and path of travel of the roll cleaner, carries a pair of cleaner rolls for rotation in spaced parallel relation thereto. The turret shaft is intermittently rotated to swing each of the cleaner rolls successively into rolling engagement with the traveling web, and then into engagement with the roll cleaner. The cleaning roll engaged with the web is urged resiliently thereagainst.